1. Field of the Invention
The present invention relates to an improved door locking device for a door closer and more particularly to a door locking device for fixing the door at predetermined angles. The locking device is for being installed between an arm which is attached to the door and a door frame and is provided with a heat detection device for automatically unlocking the door in case of a fire.
2. Description of Related Art
Door locks are generally divided into those for a general door and those for a fireproof door. The door closer provides a door, which can be fixed at a predetermined angle by adopting a locking function, an automatic closing function. The fireproof door has the function of releasing the lock automatically as a soluble body of a heat detection fuse is melted due to a temperature rise when a fire occurs while the door is open.
Various kinds of door closers with closing functions have been developed in the past, but most of them are integrally fabricated by adding a locking function and a fireproof door function to the automatic closing function which is the original function of the door closer. Such closers have a lot of defects. That is, they enable locking by the frictional force between a plate spring and a lock projection and by frictional force between the engaged gears so that locking can be performed at only one position which is very inconvenient in use. Also, the locking direction is set in only one direction without compatibility so that the left and right components must be fabricated separately, which requires increased fabrication cost.
In addition, during the lock and lock release operation, the operation is not smooth but very noisy due to friction between the lock projection and the gear.
In particular, since the door lock device is integrally fabricated with a door closer, in the case of providing a fireproof door function, it must be fabricated separately from a general door closer so that locking may be automatically released by inter-operation using a heat detection fuse which requires additional fabrication cost. Even though the friction force is reduced by the melting of a heat detection fuse, due to fire, locking between a plate spring, a lock projection and a gear which are already locked, is not released easily by reducing the frictional force. Thus, there is the concern of a malfunction and the occurrence of a malfunction is directly associated with a large fire.